Gauging apparatus



GAUGING APPARATUS Filed Feb. 5, 1966 United States Patent 3,389,595 GAUGING APPARATUS 'Michael Ernest Saxby, 01d Fletto'n,England, assignor to The Newall Engineering Company Limited, Peterborough, England, a British company Filed Feb. 3, 1966, Ser. No. 524,943 6 Claims. (Cl. 73--37.5)

ABSTRACT OF THE DISCLOSURE A gauging device having a jaw block providing a pair of jaws inclined to each other with the line of contact of the planes containing the jaw faces being parallel to the-axis of a cylindrical workpiece disposed between the jaws. A hollow tube which is moveable is disposed at a point along the line of contact. Air under pressure is passed along the said moveable hollow tube and the pressure at the end facing the workpiece is sensed. The sensed air pressure is used to guide an indication of the size of the workpiece and also to trip an automatic switch to cease a guiding operation when the workpiece has reached a predetermined size.

This invention relates to gauging devices.

According to this invention there is provided a gauging device comprising a jaw block providing a pair of jaws which are fixed in relation to each other and the opening between is wedge-shaped for enabling the jaws to engage opposite sides of a cylindrical workpiece, and an air tube which is mounted in the jaw block and projects into the Opening between the jaws, which tube is formed at its projecting end with a nozzle which, in use ofthe device, faces the surface of the workpiece at a location intermediate the points of contact of the jaws with the workpiece, and means for enabling the position of the air tube to be adjusted in a direction into and out of the opening between the jaws.

According to a preferred feature of the invention the air tube is slidably mounted in a bore in the jaw block, and releasable means is provided for securing the tube in any selected position lengthwise of the bore. Said releasable means may comprise a cotter mounted in the jaw block in a bore extending transversely of and opening to the bore in which the air tube is mounted.

In preferred constructions the device further comprises a mounting for the jaw block which mounting includes a yoke, and guide rods interconnecting the block and the yoke for movement relative to each other in a direction parallel to the direction of adjustment of the air tube, and springs urging the block and the yoke apart.

According to another preferred feature of the invention the nozzle orifice is oblong and the air tube is so held in the jaw block that the longer dimension of the nozzle orifice is parallel to the axis of a cylindrical workpiece when the workpiece is engaged by the jaws.

The jaws may conveniently be formed by a set of jaw elements which are detachable from the jaw block.

The invention further provides the combination with a gauging device as described in the preceding paragraph of at least one further set of jaw elements which are interchangeable with the first said set, and which, when positioned on the jaw block, form a wedge-shaped opening of a difierent size to that formed between the first set of jaw elements.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 shows an elevation of a gauging device, partly in cross-section,

FIGURE 2 shows an end view (with parts cut away) in the direction of the arrow 2 in FIGURE 1,

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FIGURE 3 shows a sectional end view on the line 3-3 in FIGURE 1,

FIGURE 4 is a plan, partly in section, and FIGURE 5 shows a diagrammatic view of a comparator.

gauging device comprises a jaw block 10 carrying a pair of jaw insert elements 11 and an air tube 12. The jaw elements 11 form between them a wedge-shaped opening having in the present instance an included angle of 39. The jaw elements are made from very hard material such as tungsten carbide, and are located relative to the jaw block 10 by tongues 11a formed on the rear surfaces of the insert elements, which tongues engage in corresponding grooves in the jaw block 10. In the present instance, the insert elements are secured in position on the jaw block by an adhesive. The air tube 12 is mounted in a bore in the jaw block 10, and its end projects into the wedge shaped opening.

The air tube is slidably disposed in the bore and can be secured in any selected position lengthwise of the bore by a small cotter 13 disposed in a transverse. bore in block 10. The bore containing cotter 13 opens to the bore containing air tube 12 and the cotter has a chamfered edge 14 which is engageable with the surface of the air tube to lock the air tube in position. The cotter is actuated by a screw 15 the head of which is countersunk into the jaw block 10 and which extends into a screw threaded hole in the cotter 13. On its side opposite the cotter 13, the air tube has a flat extending along part of its length and a pin 16 is mounted in a drilling in the jaw block and engages the fiat whatever the lengthwise position of air tube 12 to prevent the tube from rotating in its bore. The jaw elements are intended to engage opposite sides of a cylindrical workpiece W, and the end of the air tube has an oblong nozzle orifice, the longer dimension of which is disposed parallel to the axis of the workpiece. The pin 16 holds the air tube in the correct position in this respect. At its end remote from the jaw elements 11, the air tube 12 communicates through a block 19 with an air inlet tube 20. p

The jaw block 10 is carried on a yoke 21 by means of two rods 22. The rods 22 are secured by pins in recesses in the jaw block and project slidingly through apertures in the yoke. Compression springs 23 encircle the rods 22 between the jaw block 10 and yoke 21 to hold them resiliently apart. The yoke 21 is held captive on the rods by circlips 24 disposed in grooves near the free ends of the rods 22.

In the illustrated construction yoke 21 is in turn pivotally mounted on a. pin 25 which is fixed in the leg portion of a T-section support member 26. Member 26 is provided with holes 27 enabling the member to be secured to a suitable support structure (not shown). .An L-shaped stop 28 is secured by screws 29 to the face of yoke 21 remote from the jaw block 10, and the stop is engageable by a stop screw 30 extending through a threaded hole in a bracket 31 secured to the support member 26. Screw 30 has a lock nut 32 to enable it to be secured in any desired position relative to the bracket 31. Screw 30' and stop 28 together limit the extent to which the yoke 21 and jaw block 10 can swing downwardly under the force of gravity about the horizontal pivot pin 25. This degree of pivotal movement of the jaw block enables the jaw elements to centre the device when they engage the workpiece W.

The device shown in FIGURES 1 to 4 is intended to be mounted on a machine tool such as agrinding machine 0 in such a way that the device can be moved towards and Referring to FIGURES 1 to 4 of the drawings, the

the cylindrical workpiece, the device is moved forward until the jaw elements 11 engage opposite sides of the periphery of the workpiece. Air under pressure is supplied to the air tube 12 through the tube 20, and as the diameter of the workpiece reduces, the periphery of the workpiece, when the jaw elements 11 engage the workpiece, comes progressively nearer the nozzle orifice in the adjacent end of the air tube 12 and tends to obstruct the passage of air through the nozzle orifice. A comparator, such as that shown diagrammatically in FIGURE 5 is connected to the tube 21 and is sensitive to the attainment of the -hstruction of the orifice to a predetermined degree, corresponding to the disposition of the surface of the workpiece at a predetermined distance from the nozzle orifice and consequently to the attainment of the workpiece to a predetermined diameter. The comparator is arranged to give a signal when the predetermined obstruction of the orifice occurs and the signal is arranged to stop further machining of the workpiece.

Referring now to FIGURE the comparator is connected in the air line between a source 35 of air under pressure and the inlet tube 21 of the air tube 12. The comparator provides an inlet chamber 36 which receives air from the source 35, and the inlet chamber 36 in turn communicates through two orifices 37a, 38a with the spaces on respective opposite sides of a diaphragm 38 extending across a diaphragm chamber 39. An outlet passage 40 from the space 41 below the diaphragm leads to the inlet pipe 21. Grid members 41 are spaced above and below the diaphragm 38 to restrict the extent of deflection of the diaphragm. Above the diaphragm chamber 39 is shaped to form an upwardly extending passage on top of which is an orifice, and a tapered needle valve member 43 connected to the middle of the diaphragm extends upward through this orifice and operates a push rod 45. Rod 45 is connected to the input member 50 of a dial indicator 51 for indicating the deflection of the diaphragm 38 and carries two discs 46 for operating contacts connected to two terminals 47, 48 to control a relay for actuating termination of machining of a workpiece as previously mentioned.

When workpiece is oversize and the nozzle orifice is unobstructed, the pressure of the air in the chamber 41 below the diaphragm 38 is relatively low, and the diaphragm 38 is moved downward by the pressure of the air above the diaphragm until the effective area of nozzle 43 of the comparator increases to permit the air pressure above the diaphragm to fall to balance that acting below the diaphragm. As the obstruction of the nozzle orifice increases the pressure acting on the underside of the diaphragm 38 increases, and the diaphragm moves upwards to reduce the area of the orifice 43 to increase the pressure of the air above the diaphragm to balance this increased pressure. The resulting movement of push rod 45 eventually moves discs 46 to cause termination of machining of the workpiece.

The jaw elements 11 may if desired be replaced by another set of jaw elements providing a difierent size of wedge shaped opening and thus an extension of the range of diameters which the device can measure.

In another arrangement used in a grinding machine, the supporting member 26 and pin 27 are omitted, and the yoke 21 is pivotally mounted on the conventional steady of the machine.

I claim:

1. A gauging device comprising a jaw block providing a pair of jaws which are fixed in relation to each other, the opening between which is wedge shaped to enable the jaws to engage opposite sides of a cylindrical workpiece, an air tube which is mounted in the jaw block and projects into the opening between the jaws, which tube is formed at its projecting end with a nozzle which, when the device is in use, faces the surface of the workpiece at a location intermediate the points of contact of the jaws with the workpiece, means for enabling the position of the tube to be adjusted in a direction into and out of the opening between the jaws, and further comprising a mounting for the jaw block, which mounting includes a yoke, and guide rods interconnecting the block and the yoke for movement relative to each other in a direction parallel to the direction of adjustment of the air tube, and springs urging the block and yoke apart.

2. A gauging device as claimed in claim 1, wherein the air tube is slidably mounted in a bore in the jaw block, and releasable means is provided for securing the tube in any selected position lengthwise of the bore.

3. A gauging device as claimed in claim 2 wherein said releasable means comprises a cotter mounted in the jaw block in a bore extending transversely of and opening to the bore in which the air tube is mounted.

4. A gauging device as claimed in claim 1, wherein the nozzle orifice is rectangular and the air tube is so held in the jaw block that the longer dimension of the nozzle orifice is parallel to the axis of a cylindrical workpiece when the workpiece is engaged by the jaws.

5. A gauging device as claimed in claim 1, wherein the jaws are formed by a set of jaw elements which are detachable from the jaw block.

6. The combination with a gauging device as claimed in claim 5 of at least one further set of jaw elements which are interchangeable with the first said set, and which, when positioned on the jaw block, form a wedgeshaped opening of a different size to that formed between the first set of jaw elements.

References Cited UNITED STATES PATENTS 2,497,236 2/ 1950 Polk 73-375 1,195,330 8/1916 Binney 33-178 1,574,735 2/1926 Paloski 33-163 2,408,672 10/ 1946' Mennesson 73-375 FOREIGN PATENTS 685,416 3/1930 France. 973,471 3/ 1960 Germany.

DAVID SCHONBERG, Primary Examiner. LOUIS R. PRINCE, Examiner. WILLIAM HENRY II, Assistant Examiner. 

